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                    方法
            
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                    基于指针对象的方法
            
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                    通过嵌入结构体来扩展类型
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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        <li class="chapter " data-level="1.8.2" data-path="ch7-02.html">
            
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                    接口类型
            
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                    实现接口的条件
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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                    类型断言
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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        <li class="chapter " data-level="1.8.13" data-path="ch7-13.html">
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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                    示例: 并发的Clock服务
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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                    并发的循环
            
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                    示例: 并发的Web爬虫
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="../ch9/ch9.html">
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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        <li class="chapter " data-level="1.10.2" data-path="../ch9/ch9-02.html">
            
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                    sync.Mutex互斥锁
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
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        <li class="chapter " data-level="1.10.6" data-path="../ch9/ch9-06.html">
            
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                    竞争条件检测
            
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        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="../ch12/ch12.html">
            
                <a href="../ch12/ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="../ch12/ch12-01.html">
            
                <a href="../ch12/ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="../ch12/ch12-07.html">
            
                <a href="../ch12/ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="../ch12/ch12-08.html">
            
                <a href="../ch12/ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="../ch12/ch12-09.html">
            
                <a href="../ch12/ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
                <a href="../appendix/appendix-b-author.html">
            
                    
                    附录B：作者译者
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
                <a href="../appendix/appendix-c-cpoyright.html">
            
                    
                    附录C：译文授权
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
                <a href="../appendix/appendix-d-translations.html">
            
                    
                    附录D：其它语言
            
                </a>
            

            
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        <a href=".." >接口值</a>
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                                <h2 id="75--&#x63A5;&#x53E3;&#x503C;">7.5.  &#x63A5;&#x53E3;&#x503C;</h2>
<p>&#x6982;&#x5FF5;&#x4E0A;&#x8BB2;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x7684;&#x503C;&#xFF0C;&#x63A5;&#x53E3;&#x503C;&#xFF0C;&#x7531;&#x4E24;&#x4E2A;&#x90E8;&#x5206;&#x7EC4;&#x6210;&#xFF0C;&#x4E00;&#x4E2A;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x548C;&#x90A3;&#x4E2A;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x3002;&#x5B83;&#x4EEC;&#x88AB;&#x79F0;&#x4E3A;&#x63A5;&#x53E3;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x548C;&#x52A8;&#x6001;&#x503C;&#x3002;&#x5BF9;&#x4E8E;&#x50CF;Go&#x8BED;&#x8A00;&#x8FD9;&#x79CD;&#x9759;&#x6001;&#x7C7B;&#x578B;&#x7684;&#x8BED;&#x8A00;&#xFF0C;&#x7C7B;&#x578B;&#x662F;&#x7F16;&#x8BD1;&#x671F;&#x7684;&#x6982;&#x5FF5;&#xFF1B;&#x56E0;&#x6B64;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x4E0D;&#x662F;&#x4E00;&#x4E2A;&#x503C;&#x3002;&#x5728;&#x6211;&#x4EEC;&#x7684;&#x6982;&#x5FF5;&#x6A21;&#x578B;&#x4E2D;&#xFF0C;&#x4E00;&#x4E9B;&#x63D0;&#x4F9B;&#x6BCF;&#x4E2A;&#x7C7B;&#x578B;&#x4FE1;&#x606F;&#x7684;&#x503C;&#x88AB;&#x79F0;&#x4E3A;&#x7C7B;&#x578B;&#x63CF;&#x8FF0;&#x7B26;&#xFF0C;&#x6BD4;&#x5982;&#x7C7B;&#x578B;&#x7684;&#x540D;&#x79F0;&#x548C;&#x65B9;&#x6CD5;&#x3002;&#x5728;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x4E2D;&#xFF0C;&#x7C7B;&#x578B;&#x90E8;&#x5206;&#x4EE3;&#x8868;&#x4E0E;&#x4E4B;&#x76F8;&#x5173;&#x7C7B;&#x578B;&#x7684;&#x63CF;&#x8FF0;&#x7B26;&#x3002;</p>
<p>&#x4E0B;&#x9762;4&#x4E2A;&#x8BED;&#x53E5;&#x4E2D;&#xFF0C;&#x53D8;&#x91CF;w&#x5F97;&#x5230;&#x4E86;3&#x4E2A;&#x4E0D;&#x540C;&#x7684;&#x503C;&#x3002;&#xFF08;&#x5F00;&#x59CB;&#x548C;&#x6700;&#x540E;&#x7684;&#x503C;&#x662F;&#x76F8;&#x540C;&#x7684;&#xFF09;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> w io.Writer
w = os.Stdout
w = <span class="hljs-built_in">new</span>(bytes.Buffer)
w = <span class="hljs-literal">nil</span>
</code></pre>
<p>&#x8BA9;&#x6211;&#x4EEC;&#x8FDB;&#x4E00;&#x6B65;&#x89C2;&#x5BDF;&#x5728;&#x6BCF;&#x4E00;&#x4E2A;&#x8BED;&#x53E5;&#x540E;&#x7684;w&#x53D8;&#x91CF;&#x7684;&#x503C;&#x548C;&#x52A8;&#x6001;&#x884C;&#x4E3A;&#x3002;&#x7B2C;&#x4E00;&#x4E2A;&#x8BED;&#x53E5;&#x5B9A;&#x4E49;&#x4E86;&#x53D8;&#x91CF;w:</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> w io.Writer
</code></pre>
<p>&#x5728;Go&#x8BED;&#x8A00;&#x4E2D;&#xFF0C;&#x53D8;&#x91CF;&#x603B;&#x662F;&#x88AB;&#x4E00;&#x4E2A;&#x5B9A;&#x4E49;&#x660E;&#x786E;&#x7684;&#x503C;&#x521D;&#x59CB;&#x5316;&#xFF0C;&#x5373;&#x4F7F;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x4E5F;&#x4E0D;&#x4F8B;&#x5916;&#x3002;&#x5BF9;&#x4E8E;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x7684;&#x96F6;&#x503C;&#x5C31;&#x662F;&#x5B83;&#x7684;&#x7C7B;&#x578B;&#x548C;&#x503C;&#x7684;&#x90E8;&#x5206;&#x90FD;&#x662F;nil&#xFF08;&#x56FE;7.1&#xFF09;&#x3002;</p>
<p><img src="../images/ch7-01.png" alt=""></p>
<p>&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x57FA;&#x4E8E;&#x5B83;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x88AB;&#x63CF;&#x8FF0;&#x4E3A;&#x7A7A;&#x6216;&#x975E;&#x7A7A;&#xFF0C;&#x6240;&#x4EE5;&#x8FD9;&#x662F;&#x4E00;&#x4E2A;&#x7A7A;&#x7684;&#x63A5;&#x53E3;&#x503C;&#x3002;&#x4F60;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x4F7F;&#x7528;w==nil&#x6216;&#x8005;w!=nil&#x6765;&#x5224;&#x65AD;&#x63A5;&#x53E3;&#x503C;&#x662F;&#x5426;&#x4E3A;&#x7A7A;&#x3002;&#x8C03;&#x7528;&#x4E00;&#x4E2A;&#x7A7A;&#x63A5;&#x53E3;&#x503C;&#x4E0A;&#x7684;&#x4EFB;&#x610F;&#x65B9;&#x6CD5;&#x90FD;&#x4F1A;&#x4EA7;&#x751F;panic:</p>
<pre><code class="lang-go">w.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;hello&quot;</span>)) <span class="hljs-comment">// panic: nil pointer dereference</span>
</code></pre>
<p>&#x7B2C;&#x4E8C;&#x4E2A;&#x8BED;&#x53E5;&#x5C06;&#x4E00;&#x4E2A;<code>*os.File</code>&#x7C7B;&#x578B;&#x7684;&#x503C;&#x8D4B;&#x7ED9;&#x53D8;&#x91CF;w:</p>
<pre><code class="lang-go">w = os.Stdout
</code></pre>
<p>&#x8FD9;&#x4E2A;&#x8D4B;&#x503C;&#x8FC7;&#x7A0B;&#x8C03;&#x7528;&#x4E86;&#x4E00;&#x4E2A;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x5230;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x7684;&#x9690;&#x5F0F;&#x8F6C;&#x6362;&#xFF0C;&#x8FD9;&#x548C;&#x663E;&#x5F0F;&#x7684;&#x4F7F;&#x7528;io.Writer(os.Stdout)&#x662F;&#x7B49;&#x4EF7;&#x7684;&#x3002;&#x8FD9;&#x7C7B;&#x8F6C;&#x6362;&#x4E0D;&#x7BA1;&#x662F;&#x663E;&#x5F0F;&#x7684;&#x8FD8;&#x662F;&#x9690;&#x5F0F;&#x7684;&#xFF0C;&#x90FD;&#x4F1A;&#x523B;&#x753B;&#x51FA;&#x64CD;&#x4F5C;&#x5230;&#x7684;&#x7C7B;&#x578B;&#x548C;&#x503C;&#x3002;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x88AB;&#x8BBE;&#x4E3A;<code>*os.File</code>&#x6307;&#x9488;&#x7684;&#x7C7B;&#x578B;&#x63CF;&#x8FF0;&#x7B26;&#xFF0C;&#x5B83;&#x7684;&#x52A8;&#x6001;&#x503C;&#x6301;&#x6709;os.Stdout&#x7684;&#x62F7;&#x8D1D;&#xFF1B;&#x8FD9;&#x662F;&#x4E00;&#x4E2A;&#x4EE3;&#x8868;&#x5904;&#x7406;&#x6807;&#x51C6;&#x8F93;&#x51FA;&#x7684;os.File&#x7C7B;&#x578B;&#x53D8;&#x91CF;&#x7684;&#x6307;&#x9488;&#xFF08;&#x56FE;7.2&#xFF09;&#x3002;</p>
<p><img src="../images/ch7-02.png" alt=""></p>
<p>&#x8C03;&#x7528;&#x4E00;&#x4E2A;&#x5305;&#x542B;<code>*os.File</code>&#x7C7B;&#x578B;&#x6307;&#x9488;&#x7684;&#x63A5;&#x53E3;&#x503C;&#x7684;Write&#x65B9;&#x6CD5;&#xFF0C;&#x4F7F;&#x5F97;<code>(*os.File).Write</code>&#x65B9;&#x6CD5;&#x88AB;&#x8C03;&#x7528;&#x3002;&#x8FD9;&#x4E2A;&#x8C03;&#x7528;&#x8F93;&#x51FA;&#x201C;hello&#x201D;&#x3002;</p>
<pre><code class="lang-go">w.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;hello&quot;</span>)) <span class="hljs-comment">// &quot;hello&quot;</span>
</code></pre>
<p>&#x901A;&#x5E38;&#x5728;&#x7F16;&#x8BD1;&#x671F;&#xFF0C;&#x6211;&#x4EEC;&#x4E0D;&#x77E5;&#x9053;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x662F;&#x4EC0;&#x4E48;&#xFF0C;&#x6240;&#x4EE5;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x4E0A;&#x7684;&#x8C03;&#x7528;&#x5FC5;&#x987B;&#x4F7F;&#x7528;&#x52A8;&#x6001;&#x5206;&#x914D;&#x3002;&#x56E0;&#x4E3A;&#x4E0D;&#x662F;&#x76F4;&#x63A5;&#x8FDB;&#x884C;&#x8C03;&#x7528;&#xFF0C;&#x6240;&#x4EE5;&#x7F16;&#x8BD1;&#x5668;&#x5FC5;&#x987B;&#x628A;&#x4EE3;&#x7801;&#x751F;&#x6210;&#x5728;&#x7C7B;&#x578B;&#x63CF;&#x8FF0;&#x7B26;&#x7684;&#x65B9;&#x6CD5;Write&#x4E0A;&#xFF0C;&#x7136;&#x540E;&#x95F4;&#x63A5;&#x8C03;&#x7528;&#x90A3;&#x4E2A;&#x5730;&#x5740;&#x3002;&#x8FD9;&#x4E2A;&#x8C03;&#x7528;&#x7684;&#x63A5;&#x6536;&#x8005;&#x662F;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x52A8;&#x6001;&#x503C;&#x7684;&#x62F7;&#x8D1D;&#xFF0C;os.Stdout&#x3002;&#x6548;&#x679C;&#x548C;&#x4E0B;&#x9762;&#x8FD9;&#x4E2A;&#x76F4;&#x63A5;&#x8C03;&#x7528;&#x4E00;&#x6837;&#xFF1A;</p>
<pre><code class="lang-go">os.Stdout.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;hello&quot;</span>)) <span class="hljs-comment">// &quot;hello&quot;</span>
</code></pre>
<p>&#x7B2C;&#x4E09;&#x4E2A;&#x8BED;&#x53E5;&#x7ED9;&#x63A5;&#x53E3;&#x503C;&#x8D4B;&#x4E86;&#x4E00;&#x4E2A;*bytes.Buffer&#x7C7B;&#x578B;&#x7684;&#x503C;</p>
<pre><code class="lang-go">w = <span class="hljs-built_in">new</span>(bytes.Buffer)
</code></pre>
<p>&#x73B0;&#x5728;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x662F;*bytes.Buffer&#x5E76;&#x4E14;&#x52A8;&#x6001;&#x503C;&#x662F;&#x4E00;&#x4E2A;&#x6307;&#x5411;&#x65B0;&#x5206;&#x914D;&#x7684;&#x7F13;&#x51B2;&#x533A;&#x7684;&#x6307;&#x9488;&#xFF08;&#x56FE;7.3&#xFF09;&#x3002;</p>
<p><img src="../images/ch7-03.png" alt=""></p>
<p>Write&#x65B9;&#x6CD5;&#x7684;&#x8C03;&#x7528;&#x4E5F;&#x4F7F;&#x7528;&#x4E86;&#x548C;&#x4E4B;&#x524D;&#x4E00;&#x6837;&#x7684;&#x673A;&#x5236;&#xFF1A;</p>
<pre><code class="lang-go">w.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;hello&quot;</span>)) <span class="hljs-comment">// writes &quot;hello&quot; to the bytes.Buffers</span>
</code></pre>
<p>&#x8FD9;&#x6B21;&#x7C7B;&#x578B;&#x63CF;&#x8FF0;&#x7B26;&#x662F;*bytes.Buffer&#xFF0C;&#x6240;&#x4EE5;&#x8C03;&#x7528;&#x4E86;(*bytes.Buffer).Write&#x65B9;&#x6CD5;&#xFF0C;&#x5E76;&#x4E14;&#x63A5;&#x6536;&#x8005;&#x662F;&#x8BE5;&#x7F13;&#x51B2;&#x533A;&#x7684;&#x5730;&#x5740;&#x3002;&#x8FD9;&#x4E2A;&#x8C03;&#x7528;&#x628A;&#x5B57;&#x7B26;&#x4E32;&#x201C;hello&#x201D;&#x6DFB;&#x52A0;&#x5230;&#x7F13;&#x51B2;&#x533A;&#x4E2D;&#x3002;</p>
<p>&#x6700;&#x540E;&#xFF0C;&#x7B2C;&#x56DB;&#x4E2A;&#x8BED;&#x53E5;&#x5C06;nil&#x8D4B;&#x7ED9;&#x4E86;&#x63A5;&#x53E3;&#x503C;&#xFF1A;</p>
<pre><code class="lang-go">w = <span class="hljs-literal">nil</span>
</code></pre>
<p>&#x8FD9;&#x4E2A;&#x91CD;&#x7F6E;&#x5C06;&#x5B83;&#x6240;&#x6709;&#x7684;&#x90E8;&#x5206;&#x90FD;&#x8BBE;&#x4E3A;nil&#x503C;&#xFF0C;&#x628A;&#x53D8;&#x91CF;w&#x6062;&#x590D;&#x5230;&#x548C;&#x5B83;&#x4E4B;&#x524D;&#x5B9A;&#x4E49;&#x65F6;&#x76F8;&#x540C;&#x7684;&#x72B6;&#x6001;&#xFF0C;&#x5728;&#x56FE;7.1&#x4E2D;&#x53EF;&#x4EE5;&#x770B;&#x5230;&#x3002;</p>
<p>&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x53EF;&#x4EE5;&#x6301;&#x6709;&#x4EFB;&#x610F;&#x5927;&#x7684;&#x52A8;&#x6001;&#x503C;&#x3002;&#x4F8B;&#x5982;&#xFF0C;&#x8868;&#x793A;&#x65F6;&#x95F4;&#x5B9E;&#x4F8B;&#x7684;time.Time&#x7C7B;&#x578B;&#xFF0C;&#x8FD9;&#x4E2A;&#x7C7B;&#x578B;&#x6709;&#x51E0;&#x4E2A;&#x5BF9;&#x5916;&#x4E0D;&#x516C;&#x5F00;&#x7684;&#x5B57;&#x6BB5;&#x3002;&#x6211;&#x4EEC;&#x4ECE;&#x5B83;&#x4E0A;&#x9762;&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> x <span class="hljs-keyword">interface</span>{} = time.Now()
</code></pre>
<p>&#x7ED3;&#x679C;&#x53EF;&#x80FD;&#x548C;&#x56FE;7.4&#x76F8;&#x4F3C;&#x3002;&#x4ECE;&#x6982;&#x5FF5;&#x4E0A;&#x8BB2;&#xFF0C;&#x4E0D;&#x8BBA;&#x63A5;&#x53E3;&#x503C;&#x591A;&#x5927;&#xFF0C;&#x52A8;&#x6001;&#x503C;&#x603B;&#x662F;&#x53EF;&#x4EE5;&#x5BB9;&#x4E0B;&#x5B83;&#x3002;&#xFF08;&#x8FD9;&#x53EA;&#x662F;&#x4E00;&#x4E2A;&#x6982;&#x5FF5;&#x4E0A;&#x7684;&#x6A21;&#x578B;&#xFF1B;&#x5177;&#x4F53;&#x7684;&#x5B9E;&#x73B0;&#x53EF;&#x80FD;&#x4F1A;&#x975E;&#x5E38;&#x4E0D;&#x540C;&#xFF09;</p>
<p><img src="../images/ch7-04.png" alt=""></p>
<p>&#x63A5;&#x53E3;&#x503C;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;==&#x548C;!&#xFF1D;&#x6765;&#x8FDB;&#x884C;&#x6BD4;&#x8F83;&#x3002;&#x4E24;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x76F8;&#x7B49;&#x4EC5;&#x5F53;&#x5B83;&#x4EEC;&#x90FD;&#x662F;nil&#x503C;&#xFF0C;&#x6216;&#x8005;&#x5B83;&#x4EEC;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x76F8;&#x540C;&#x5E76;&#x4E14;&#x52A8;&#x6001;&#x503C;&#x4E5F;&#x6839;&#x636E;&#x8FD9;&#x4E2A;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x7684;==&#x64CD;&#x4F5C;&#x76F8;&#x7B49;&#x3002;&#x56E0;&#x4E3A;&#x63A5;&#x53E3;&#x503C;&#x662F;&#x53EF;&#x6BD4;&#x8F83;&#x7684;&#xFF0C;&#x6240;&#x4EE5;&#x5B83;&#x4EEC;&#x53EF;&#x4EE5;&#x7528;&#x5728;map&#x7684;&#x952E;&#x6216;&#x8005;&#x4F5C;&#x4E3A;switch&#x8BED;&#x53E5;&#x7684;&#x64CD;&#x4F5C;&#x6570;&#x3002;</p>
<p>&#x7136;&#x800C;&#xFF0C;&#x5982;&#x679C;&#x4E24;&#x4E2A;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x76F8;&#x540C;&#xFF0C;&#x4F46;&#x662F;&#x8FD9;&#x4E2A;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x662F;&#x4E0D;&#x53EF;&#x6BD4;&#x8F83;&#x7684;&#xFF08;&#x6BD4;&#x5982;&#x5207;&#x7247;&#xFF09;&#xFF0C;&#x5C06;&#x5B83;&#x4EEC;&#x8FDB;&#x884C;&#x6BD4;&#x8F83;&#x5C31;&#x4F1A;&#x5931;&#x8D25;&#x5E76;&#x4E14;panic:</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> x <span class="hljs-keyword">interface</span>{} = []<span class="hljs-keyword">int</span>{<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>}
fmt.Println(x == x) <span class="hljs-comment">// panic: comparing uncomparable type []int</span>
</code></pre>
<p>&#x8003;&#x8651;&#x5230;&#x8FD9;&#x70B9;&#xFF0C;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x662F;&#x975E;&#x5E38;&#x4E0E;&#x4F17;&#x4E0D;&#x540C;&#x7684;&#x3002;&#x5176;&#x5B83;&#x7C7B;&#x578B;&#x8981;&#x4E48;&#x662F;&#x5B89;&#x5168;&#x7684;&#x53EF;&#x6BD4;&#x8F83;&#x7C7B;&#x578B;&#xFF08;&#x5982;&#x57FA;&#x672C;&#x7C7B;&#x578B;&#x548C;&#x6307;&#x9488;&#xFF09;&#x8981;&#x4E48;&#x662F;&#x5B8C;&#x5168;&#x4E0D;&#x53EF;&#x6BD4;&#x8F83;&#x7684;&#x7C7B;&#x578B;&#xFF08;&#x5982;&#x5207;&#x7247;&#xFF0C;&#x6620;&#x5C04;&#x7C7B;&#x578B;&#xFF0C;&#x548C;&#x51FD;&#x6570;&#xFF09;&#xFF0C;&#x4F46;&#x662F;&#x5728;&#x6BD4;&#x8F83;&#x63A5;&#x53E3;&#x503C;&#x6216;&#x8005;&#x5305;&#x542B;&#x4E86;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x805A;&#x5408;&#x7C7B;&#x578B;&#x65F6;&#xFF0C;&#x6211;&#x4EEC;&#x5FC5;&#x987B;&#x8981;&#x610F;&#x8BC6;&#x5230;&#x6F5C;&#x5728;&#x7684;panic&#x3002;&#x540C;&#x6837;&#x7684;&#x98CE;&#x9669;&#x4E5F;&#x5B58;&#x5728;&#x4E8E;&#x4F7F;&#x7528;&#x63A5;&#x53E3;&#x4F5C;&#x4E3A;map&#x7684;&#x952E;&#x6216;&#x8005;switch&#x7684;&#x64CD;&#x4F5C;&#x6570;&#x3002;&#x53EA;&#x80FD;&#x6BD4;&#x8F83;&#x4F60;&#x975E;&#x5E38;&#x786E;&#x5B9A;&#x5B83;&#x4EEC;&#x7684;&#x52A8;&#x6001;&#x503C;&#x662F;&#x53EF;&#x6BD4;&#x8F83;&#x7C7B;&#x578B;&#x7684;&#x63A5;&#x53E3;&#x503C;&#x3002;</p>
<p>&#x5F53;&#x6211;&#x4EEC;&#x5904;&#x7406;&#x9519;&#x8BEF;&#x6216;&#x8005;&#x8C03;&#x8BD5;&#x7684;&#x8FC7;&#x7A0B;&#x4E2D;&#xFF0C;&#x5F97;&#x77E5;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x662F;&#x975E;&#x5E38;&#x6709;&#x5E2E;&#x52A9;&#x7684;&#x3002;&#x6240;&#x4EE5;&#x6211;&#x4EEC;&#x4F7F;&#x7528;fmt&#x5305;&#x7684;%T&#x52A8;&#x4F5C;:</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> w io.Writer
fmt.Printf(<span class="hljs-string">&quot;%T\n&quot;</span>, w) <span class="hljs-comment">// &quot;&lt;nil&gt;&quot;</span>
w = os.Stdout
fmt.Printf(<span class="hljs-string">&quot;%T\n&quot;</span>, w) <span class="hljs-comment">// &quot;*os.File&quot;</span>
w = <span class="hljs-built_in">new</span>(bytes.Buffer)
fmt.Printf(<span class="hljs-string">&quot;%T\n&quot;</span>, w) <span class="hljs-comment">// &quot;*bytes.Buffer&quot;</span>
</code></pre>
<p>&#x5728;fmt&#x5305;&#x5185;&#x90E8;&#xFF0C;&#x4F7F;&#x7528;&#x53CD;&#x5C04;&#x6765;&#x83B7;&#x53D6;&#x63A5;&#x53E3;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x7684;&#x540D;&#x79F0;&#x3002;&#x6211;&#x4EEC;&#x4F1A;&#x5728;&#x7B2C;12&#x7AE0;&#x4E2D;&#x5B66;&#x5230;&#x53CD;&#x5C04;&#x76F8;&#x5173;&#x7684;&#x77E5;&#x8BC6;&#x3002;</p>
<h3 id="751--&#x8B66;&#x544A;&#xFF1A;&#x4E00;&#x4E2A;&#x5305;&#x542B;nil&#x6307;&#x9488;&#x7684;&#x63A5;&#x53E3;&#x4E0D;&#x662F;nil&#x63A5;&#x53E3;">7.5.1.  &#x8B66;&#x544A;&#xFF1A;&#x4E00;&#x4E2A;&#x5305;&#x542B;nil&#x6307;&#x9488;&#x7684;&#x63A5;&#x53E3;&#x4E0D;&#x662F;nil&#x63A5;&#x53E3;</h3>
<p>&#x4E00;&#x4E2A;&#x4E0D;&#x5305;&#x542B;&#x4EFB;&#x4F55;&#x503C;&#x7684;nil&#x63A5;&#x53E3;&#x503C;&#x548C;&#x4E00;&#x4E2A;&#x521A;&#x597D;&#x5305;&#x542B;nil&#x6307;&#x9488;&#x7684;&#x63A5;&#x53E3;&#x503C;&#x662F;&#x4E0D;&#x540C;&#x7684;&#x3002;&#x8FD9;&#x4E2A;&#x7EC6;&#x5FAE;&#x533A;&#x522B;&#x4EA7;&#x751F;&#x4E86;&#x4E00;&#x4E2A;&#x5BB9;&#x6613;&#x7ECA;&#x5012;&#x6BCF;&#x4E2A;Go&#x7A0B;&#x5E8F;&#x5458;&#x7684;&#x9677;&#x9631;&#x3002;</p>
<p>&#x601D;&#x8003;&#x4E0B;&#x9762;&#x7684;&#x7A0B;&#x5E8F;&#x3002;&#x5F53;debug&#x53D8;&#x91CF;&#x8BBE;&#x7F6E;&#x4E3A;true&#x65F6;&#xFF0C;main&#x51FD;&#x6570;&#x4F1A;&#x5C06;f&#x51FD;&#x6570;&#x7684;&#x8F93;&#x51FA;&#x6536;&#x96C6;&#x5230;&#x4E00;&#x4E2A;bytes.Buffer&#x7C7B;&#x578B;&#x4E2D;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">const</span> debug = <span class="hljs-literal">true</span>

<span class="hljs-keyword">func</span> main() {
    <span class="hljs-keyword">var</span> buf *bytes.Buffer
    <span class="hljs-keyword">if</span> debug {
        buf = <span class="hljs-built_in">new</span>(bytes.Buffer) <span class="hljs-comment">// enable collection of output</span>
    }
    f(buf) <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> subtly incorrect!</span>
    <span class="hljs-keyword">if</span> debug {
        <span class="hljs-comment">// ...use buf...</span>
    }
}

<span class="hljs-comment">// If out is non-nil, output will be written to it.</span>
<span class="hljs-keyword">func</span> f(out io.Writer) {
    <span class="hljs-comment">// ...do something...</span>
    <span class="hljs-keyword">if</span> out != <span class="hljs-literal">nil</span> {
        out.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;done!\n&quot;</span>))
    }
}
</code></pre>
<p>&#x6211;&#x4EEC;&#x53EF;&#x80FD;&#x4F1A;&#x9884;&#x8BA1;&#x5F53;&#x628A;&#x53D8;&#x91CF;debug&#x8BBE;&#x7F6E;&#x4E3A;false&#x65F6;&#x53EF;&#x4EE5;&#x7981;&#x6B62;&#x5BF9;&#x8F93;&#x51FA;&#x7684;&#x6536;&#x96C6;&#xFF0C;&#x4F46;&#x662F;&#x5B9E;&#x9645;&#x4E0A;&#x5728;out.Write&#x65B9;&#x6CD5;&#x8C03;&#x7528;&#x65F6;&#x7A0B;&#x5E8F;&#x53D1;&#x751F;&#x4E86;panic&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">if</span> out != <span class="hljs-literal">nil</span> {
    out.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;done!\n&quot;</span>)) <span class="hljs-comment">// panic: nil pointer dereference</span>
}
</code></pre>
<p>&#x5F53;main&#x51FD;&#x6570;&#x8C03;&#x7528;&#x51FD;&#x6570;f&#x65F6;&#xFF0C;&#x5B83;&#x7ED9;f&#x51FD;&#x6570;&#x7684;out&#x53C2;&#x6570;&#x8D4B;&#x4E86;&#x4E00;&#x4E2A;*bytes.Buffer&#x7684;&#x7A7A;&#x6307;&#x9488;&#xFF0C;&#x6240;&#x4EE5;out&#x7684;&#x52A8;&#x6001;&#x503C;&#x662F;nil&#x3002;&#x7136;&#x800C;&#xFF0C;&#x5B83;&#x7684;&#x52A8;&#x6001;&#x7C7B;&#x578B;&#x662F;*bytes.Buffer&#xFF0C;&#x610F;&#x601D;&#x5C31;&#x662F;out&#x53D8;&#x91CF;&#x662F;&#x4E00;&#x4E2A;&#x5305;&#x542B;&#x7A7A;&#x6307;&#x9488;&#x503C;&#x7684;&#x975E;&#x7A7A;&#x63A5;&#x53E3;&#xFF08;&#x5982;&#x56FE;7.5&#xFF09;&#xFF0C;&#x6240;&#x4EE5;&#x9632;&#x5FA1;&#x6027;&#x68C0;&#x67E5;out!=nil&#x7684;&#x7ED3;&#x679C;&#x4F9D;&#x7136;&#x662F;true&#x3002;</p>
<p><img src="../images/ch7-05.png" alt=""></p>
<p>&#x52A8;&#x6001;&#x5206;&#x914D;&#x673A;&#x5236;&#x4F9D;&#x7136;&#x51B3;&#x5B9A;(*bytes.Buffer).Write&#x7684;&#x65B9;&#x6CD5;&#x4F1A;&#x88AB;&#x8C03;&#x7528;&#xFF0C;&#x4F46;&#x662F;&#x8FD9;&#x6B21;&#x7684;&#x63A5;&#x6536;&#x8005;&#x7684;&#x503C;&#x662F;nil&#x3002;&#x5BF9;&#x4E8E;&#x4E00;&#x4E9B;&#x5982;*os.File&#x7684;&#x7C7B;&#x578B;&#xFF0C;nil&#x662F;&#x4E00;&#x4E2A;&#x6709;&#x6548;&#x7684;&#x63A5;&#x6536;&#x8005;&#xFF08;&#xA7;6.2.1&#xFF09;&#xFF0C;&#x4F46;&#x662F;*bytes.Buffer&#x7C7B;&#x578B;&#x4E0D;&#x5728;&#x8FD9;&#x4E9B;&#x79CD;&#x7C7B;&#x4E2D;&#x3002;&#x8FD9;&#x4E2A;&#x65B9;&#x6CD5;&#x4F1A;&#x88AB;&#x8C03;&#x7528;&#xFF0C;&#x4F46;&#x662F;&#x5F53;&#x5B83;&#x5C1D;&#x8BD5;&#x53BB;&#x83B7;&#x53D6;&#x7F13;&#x51B2;&#x533A;&#x65F6;&#x4F1A;&#x53D1;&#x751F;panic&#x3002;</p>
<p>&#x95EE;&#x9898;&#x5728;&#x4E8E;&#x5C3D;&#x7BA1;&#x4E00;&#x4E2A;nil&#x7684;*bytes.Buffer&#x6307;&#x9488;&#x6709;&#x5B9E;&#x73B0;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x5B83;&#x4E5F;&#x4E0D;&#x6EE1;&#x8DB3;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x5177;&#x4F53;&#x7684;&#x884C;&#x4E3A;&#x4E0A;&#x7684;&#x8981;&#x6C42;&#x3002;&#x7279;&#x522B;&#x662F;&#x8FD9;&#x4E2A;&#x8C03;&#x7528;&#x8FDD;&#x53CD;&#x4E86;(*bytes.Buffer).Write&#x65B9;&#x6CD5;&#x7684;&#x63A5;&#x6536;&#x8005;&#x975E;&#x7A7A;&#x7684;&#x9690;&#x542B;&#x5148;&#x89C9;&#x6761;&#x4EF6;&#xFF0C;&#x6240;&#x4EE5;&#x5C06;nil&#x6307;&#x9488;&#x8D4B;&#x7ED9;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x662F;&#x9519;&#x8BEF;&#x7684;&#x3002;&#x89E3;&#x51B3;&#x65B9;&#x6848;&#x5C31;&#x662F;&#x5C06;main&#x51FD;&#x6570;&#x4E2D;&#x7684;&#x53D8;&#x91CF;buf&#x7684;&#x7C7B;&#x578B;&#x6539;&#x4E3A;io.Writer&#xFF0C;&#x56E0;&#x6B64;&#x53EF;&#x4EE5;&#x907F;&#x514D;&#x4E00;&#x5F00;&#x59CB;&#x5C31;&#x5C06;&#x4E00;&#x4E2A;&#x4E0D;&#x5B8C;&#x6574;&#x7684;&#x503C;&#x8D4B;&#x503C;&#x7ED9;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> buf io.Writer
<span class="hljs-keyword">if</span> debug {
    buf = <span class="hljs-built_in">new</span>(bytes.Buffer) <span class="hljs-comment">// enable collection of output</span>
}
f(buf) <span class="hljs-comment">// OK</span>
</code></pre>
<p>&#x73B0;&#x5728;&#x6211;&#x4EEC;&#x5DF2;&#x7ECF;&#x628A;&#x63A5;&#x53E3;&#x503C;&#x7684;&#x6280;&#x5DE7;&#x90FD;&#x8BB2;&#x5B8C;&#x4E86;&#xFF0C;&#x8BA9;&#x6211;&#x4EEC;&#x6765;&#x770B;&#x66F4;&#x591A;&#x7684;&#x4E00;&#x4E9B;&#x5728;Go&#x6807;&#x51C6;&#x5E93;&#x4E2D;&#x7684;&#x91CD;&#x8981;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x3002;&#x5728;&#x4E0B;&#x9762;&#x7684;&#x4E09;&#x7AE0;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x4F1A;&#x770B;&#x5230;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x662F;&#x600E;&#x6837;&#x7528;&#x5728;&#x6392;&#x5E8F;&#xFF0C;web&#x670D;&#x52A1;&#xFF0C;&#x9519;&#x8BEF;&#x5904;&#x7406;&#x4E2D;&#x7684;&#x3002;</p>

                                
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